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anatomy > Test 3 -Skeletal Muscle > Flashcards

Test 3 -Skeletal Muscle Flashcards

1
Q

Muscle

A

Little mouse

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2
Q

Muscle functions

A
  • movement
  • maintenance of posture
  • join stabilization
  • heat generation
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3
Q

movement of muscle

A

skeletal muscle attaches to the skeleton and moves the body by moving the bones

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4
Q

maintenance of posture

muscle function

A

certain skeletal muscles contract continuously to maintain posture, enabling the body to remain in standing or sitting position

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5
Q 
join stabilization
(muscle function)
A

muscle tone is a constant, low level of contractile force that is generated by a muscle even when it is not causing movement

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6
Q

muscle tone stabilizes joints by?

A

keeping tension on the muscle tendons that cross over joints just external to the join capsule

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7
Q 
heat generation
(muscle function)
A

muscle contractions produce heat that plays a vital role in maintaining normal body temperature at 98.6 F (37 C)

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8
Q

what are some special functional characteristics of muscle tissue that distinguish it from other tissues

A

contractility
excitability
extensibility
elasticity

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9
Q

contractability of muscles

A
  • muscle cells shorten and generate a strong pulling force as they contract
  • actin and myosin
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10
Q

excitability of muscles

A

nerve signals or other factors excite muscle cells, causing electrical impulses to travel along the cell’s plasma membrane, causing the cells to conract

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11
Q

extensibility of muscles

A

muscle tissue can be stretched by the contraction of an opposing muscle

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12
Q

elasticity of muscles

A

after being stretched, muscle tissue can recoil passively and resume its resting lenght

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13
Q

what are the three types of muscle tissue?

A

skeletal
cardiac
smooth

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14
Q

each type of muscle tissues can be characterized by what two main features?

A
  1. the presence or absence of striations in the muscle cells

2. whether control is voluntary or involuntary

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15
Q

striated vs nonstriated

A
  1. striated muscle tissue has stripes extending transversely across the muscle cells
  2. nonstriated muscle does not have the distinctive bands of striation
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16
Q

in muscles voluntary and involuntary refers to?

A

to the innervation of the muscle tissue

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17
Q

voluntary muscle

A

innervated by voluntary motor nerves and subject to conscious control
- you can control this muscle tissue at will

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18
Q

involuntary muscle

A

innervated by the involuntary portion of the nervous system and cannot be controlled consciously

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19
Q

skeletal muscle tissue

A

-located in the skeletal muscle, discrete organs that attach to and move
the skeleton
- make up 40% of the body weight
- cells are striated
- contractions is subject to voluntary control

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20
Q

cardiac muscle tissue

A
  • occurs only in the walls of the heart
  • cells are striated
  • contractions is subject to involuntary control
  • visceral muscle
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21
Q

smooth muscle tissue

A
  • most found in the walls of hollow internal organs
  • cells lack striations
  • contractions is subject to involuntary control
  • visceral muscle
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22
Q

what is an important similarities between skeletal and smooth muscles only

A

the cells of skeletal and smooth muscle tissu (only) are called fibers because they are elongated

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23
Q

in all three types of muscle tissue, muscle contractions depend on?

A

myofilaments

- specific types of microfilaments that are responsible for the shortening of muscle cells

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24
Q

the plasma membrane of muscle cells are called?

A

sarcolemma

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25
Q

the cytoplasm of muscle cells are called?

A

sarcoplasm

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26
Q

does the function of cytoplasm in comparison to sarcoplams or plasma membrane to sarcolemma differ?

A

no. they are the same, just different name

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27
Q

what holds the fibers of a skeletal muscles together?

A

several sheath of connective tissue
from external to internal:
- epimysium -> perimysium -> endomysium

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28
Q

epimysium

A
  • “outside the muscle”

- an overcoat of dense, irregular C.T that surrounds the whole skeletal muscle

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29
Q

perimysium

A
  • “around the muscle”

- a layer of fibrous C.T. that surrounds each fascicle

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30
Q

fascicle

A

a group of muscle fibers

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31
Q

endomysium

A
  • “within the muscle”

- a fine sheath of C.T. consisting mostly of reticular fibers that surrounds each muscle fiber within each fascicle

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32
Q

What are the function of the fibrous connective tissue of skeletal muscles?

A

binds muscle fibers together and hold them in parallel alignment so they can work together to produce force

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33
Q

all three sheaths are continuous with?

A

with the tendon

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34
Q

tendon

A

the connective tissue structure that joins skeletal muscle to bones

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35
Q

what happens when muscle fibers contract?

A

they pull on the surrounding endomysium

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36
Q

Because of the continuity between sheath what happens after the surrounding endomysium is pulled?

A

the pull is then exerted on the perimysium, epimysium, and tendon

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37
Q

what else does the sheath provide?

A

provide a muscle with much of its elasticity and carry the blood vessels and nerves that serve the muscle fibers

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38
Q

in general, each skeletal muscle is supplied by?

A

one nerve, one artery, and one or more veins

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39
Q

where does the nerve, artery, and veins all enter or exit the muscle?

A

near the middle of its lenght

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40
Q

the nerves and vessels branch repeatedly where?

A

branch repeatedly in the intramuscular CT, with the smallest branches serving individual muscle fibers

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41
Q

capillaries of the skeletal muscle form a network within the

A

endomysium

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42
Q

the rich blood supply to muscles reflects the?

A

high demand that contracting muscle fibers have for nutrients and oxygen

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43
Q

the smallest nerve branches serve?

A

individual muscle fibers

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44
Q

what is neuromuscular joints?

A

interface between nerve and muscle fiber

synaptic cleft between neuron and muscle fibers

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45
Q

what is a muscle attachement

A

the location on a bone where a muscle connects to the bone

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46
Q

each skeletal muscle extends from?

A

one bone to another crossing at least one movable join

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47
Q

what happens when a muscle contracts?

A

it causes one of the bones to move while the other bone usually remains fixed

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48
Q

the attachment of the muscle on the less movable bone is called?

A

the origin of the muscle

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49
Q

the attachment on the more moveable bone is called?

A

(the muscle’s) Insertion

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50
Q

when muscle contracts what happens between insertion and origin?

A

muscles insertion is pulled towards its origin

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51
Q

in the muscle of the limbs, the origin is?

A

the more proximal attachment of the muscle

52
Q

in the muscles of the limbs, the insertion is?

A

the more distal attachment

53
Q

the origin and insertion of a given muscle can be at either attachment of the muscle, depending on?

A

a. what position of the body is in

b. the movement is produced as the muscle contracts

54
Q

muscles attach to their origins and insertions via?

A

strong fibrous periosteum of the bone

55
Q

what happens in direct or fleshy attachments

A

the attaching strands of the CT are so short that the muscle fascicles themselves appear to attach directly to the bone

56
Q

in indirect attachments, the ct?

A

Connective tissues extends well beyond the end of the muscle fibers to form either a cordlike tendon or a flat sheet called aponeurosis

57
Q

Which are more common attachments?

A

indirect attachments are more common than direct attachments and most muscles have tendons

58
Q

raised bone markings are often present where?

A

where tendons meet bones (eg Greater trochanter)

59
Q

microscopic anatomy of skeletal muscle fiber

A

skeletal muscle fibers are long, cyndrical cells

  • diameter 10 - 100 um
  • lenght: several cm (short muscles) to dozens of cm (long muscles
60
Q

each skeletal muscle fiber is formed by?

A

the fusion of hundreds of embryonic cells.

- contains many nuclei

61
Q

where are the nuclei located in skeletal muscle fibers?

A

they lie in the periphery of each fiber, just deep to the sacrolemma

62
Q

the striations of skeletal muscle fibers are the result from?

A

from the internal structure of long, rod-shaped organelles called myofibrils

63
Q

myofibrils

A

specialized contractile organelles unique to muscle tissue that make up more than 80% of the sacroplasm
- a long row of repeating segments called sarcomeres

64
Q

sarcomeres

A
  • “muscle segments”

- the basic unit of contraction

65
Q

Z-discs or Z-lines

A

the boundaries at the two ends of each sarcomere are called?

66
Q

where are actin filaments located?

A

attached to each Z-disc and extending towards the center of the sacromere

67
Q

actin filaments

A
  • (fine myofilaments) thin filaments which consist primarily of the protein actin
68
Q

myosin filaments

A

cylindrical bundle of thick filaments that consists primarily of myosin molecules

69
Q

where are myosin molecules located?

A

in the center of the sacromere and overlapping the inner ends of the thin filaments

70
Q

myosin filaments also contains what enzyme?

A

ATPase enzymes that split ATP to release the energy required for muscle contractions

71
Q

the sarcomere structrue explains?

A

the pattern of striations in skeletal muscle fibers

72
Q

the dark bands are created by?

A

the full length of the thick filaments in the sarcomeres, along with the inner ends of the thin filaments

73
Q

what region is dark bands in?

A

the A band

74
Q

H zone

A
  • central part of an A band,

- no thin filaments reach

75
Q

M line

A
  • in the center of the H-zone

- contains tiny rods that hold the thick filaments together

76
Q

I bands

A

the two regions on either side of the A band, which contains only thin filaments

77
Q

I bands forms which bands?

A

light bands

78
Q

each skeletal muscle fiber contains two sets of?

A

two sets of tubules that participate in the regulation of muscle contraction

79
Q

what are the two set of tubules in the skeletal muscle fiber

A
  1. sarcoplasmic reticulum (SR)

2. T tubules

80
Q

Sarcoplasmic reticulum (SR)

A

an elaborate smooth endoplasmic reticulum whose interconnecting tubules surround each myofibril and run longitudinally along the myofibril

81
Q

terminal cisternae

A
  • “end sacs”

- larger perpendicular cross-channels over the junction between the A bands and I bands

82
Q

The sacroplasmic reticulum stores ?

A

large quantities of calcium ions Ca2+

83
Q

when are calcium ions released?

A

when the muscle is stimulated to contract

84
Q

Ca2+ ions actions

A
  • diffuse through the cytosol to the thin filaments, where they trigger the sliding filament mechanism of contraction
  • after the contraction, the Ca@+ ions are pumped back into the SR for storage
85
Q

muscular contraction in skeletal muscle is controlled by?

A

nerve generated impulses that travel along the sarcolemma of the muscle cell then these impulses are further conducted by T tubules

86
Q

T tubules

A

deep invaginations of the sarcolemma that run between each pair of terminal cisternae of the sarcoplasmic reticulum

87
Q

Because T tubules are continuations of the sarcolemma they conduct each impulse to?

A

they conduct each impulse to the deepest regions of the muscle fiber

88
Q

Triad

T-tubules

A

the complext of a T tubule with flanked by two terminal cisternae at each A-I junction

89
Q

the two types of muscle contraction involved in producing movements

A
  1. concentric contraction

2. eccentric contraction

90
Q

concentric contraction

A

the shortens and does work

91
Q

eccentric contraction

A

a muscle generates force as it lengthens

- essential for controlled movement and resistance to gravity

92
Q

when muscles are acting “like a brake” they are contracting?

A

eccentrically

- landing from a jump

93
Q

what explains concentric contractions of skeletal muscle?

A

sliding filament mechanism

94
Q

sliding filament mechanism

A
  • actin + myosin + cross bridges
  • contraction results as the myosin heads of the thick filaments attach to the thin filaments at both ends of the sarcomere and pull the thin filaments toward the center of the sarcomere by swiveling inward
95
Q

sliding filament mechanism

- what happens after a myosin head pivots at its hinges?

A

it lets go, returns to its original position, binds to the thin filament farther along its length and pivots again

96
Q

the ratchet-like cycle of the sliding filament mechanism during a single contraction is?

A

repeated many times

- the thick and thin filaments do not shorten, they merely slide past one another

97
Q

the sliding filament mechanism is initiated by ?

A

the release of Ca2+ ions from the SR and the binding of those ions to the thin filaments

98
Q

Sliding filament mechanism is powered by?

A

ATP

99
Q

what does the action of the thick filaments do?

A

pulls the two Z discs closer together, causing each sarcomere to shorten

a) causing the I bands to shorten
b) causing the H zones to disappear completely

100
Q

Why does the A bands stay the same lenght?

A

because the length of the thick filaments does not change

101
Q

the optimal resting length for skeletal muscle fibers is?

A

the lenght that will generate the greatest pulling force when the muscle is contracted

102
Q

what is the optimal resting length?

A

i dont know

103
Q

When does the optimal length occurs?

A

when a fiber is slightly stretched so that its thin and thick filaments overlap only to a moderate extent..Why?

104
Q

skeletal muscles range of optimal operational lenght

A

runs from about 80% of their normal resting lenght to about 120% of that length

105
Q

joins normal actions

A

do not let any bone move so widely that its attached muscles could not shorten or stretch beyond their optimal range

106
Q

titin

A

a spring like molecule in sarcomeres that resists overstretching

107
Q

where does the titin molecules in a sarcomere extend from?

A

from the Z disc to the thick filament and run within the thick filament to attach to the M line

108
Q

caridac muscle

A

the muscle tissue of the heart wall

109
Q

myocardium

A

thick layer formed by the cardiac muscle

110
Q

contraction of the cardiac muscle does what

A

pump blood through the blood vessels of the circulatory system

111
Q

cardiac muscle - discription

A

striated like skeletal muscle and it contracts through the sliding filament mechanism

112
Q

what kind of cell are cardiac muscles?

A

single cells separated from one another by a delicate endomysium
- each cell contains one or two neuclei in its center, not at periphery

113
Q

are cardiac muscle cells called fibers?

A

no

114
Q

what is unique to cardiac muscle?

A

its cells branch and join together at complex junctions called intercalated discs so that they form cellular network

115
Q

what are the three types of cell junctions that intercalated discs have?

A

desmosomes
fasciae adherans
gap junction

116
Q

fasciae adherans

A

long, desmosome-like junctions

117
Q

desmosomes and fasciae adherans function

A

hold the cells together

118
Q

gap junction function

A

allow ions to pass between cells

119
Q

where are most smooth muscle of the body found?

A

walls of viceral organs that contracts via the slliding filament mechanism

120
Q

six major location of smooth muscle

A
  1. inside the eye
    * ***in the walls of the
  2. circulatory vessels
  3. respiratory vessels
  4. digestie tubes
  5. urinary organs
  6. reproductive organs
121
Q

each smooth muscle fiber is a?

A

spindle shaped cell with one centrally located nucleus

  • cells are separated by endomysium
  • no s`triations or sarcomeres
122
Q

what fills the sacroplasm of smooth muscle?

A

interdigitating thick and thin filaments

123
Q

the fibers of smooth muscles in the walls of hollow viscera are?

A

grouped into sheets of smooth muscle tissue

- often two sheets are present, with their fibers oriented at right angles to each other

124
Q

smooth muscle layers

A
  1. longitudinal layer

2. circular layer

125
Q

circular layer and longitudinal layer of smooth muscle

A
  • circular layer constricts the hollow organ

- longitudinal layer shortens the organ’s lenght

126
Q

peristalsis

A
  • around contraction
  • a process by which the circular layer and longtitudinal muscle layers generate alternate waves of contraction and relaxation that propel substance through the organ

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